Thrombectomy devices with aspiration

ABSTRACT

A thrombectomy device includes a handle at a proximal end portion of the device, a cage at a distal end portion of the device, the cage being moveable between an expanded orientation and a contracted orientation, and a first tube extending from the proximal end portion of the device to at least a proximal end portion of the cage. The device also includes a second tube extending from the proximal end portion of the device to at least a distal end portion of the cage, and a self-adjusting control assembly including a biasing element coupled to one of the first tube or the second tube. The biasing element exerts an axial force to urge the cage toward the expanded orientation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/133,111, filed Dec. 23, 2020, which is a continuation of U.S.application Ser. No. 15/936,635, filed Mar. 27, 2018, which is acontinuation of U.S. application Ser. No. 15/008,057, filed Jan. 27,2016, which is a continuation of U.S. application Ser. No. 14/776,633,filed Sep. 14, 2015, which is the U.S. national phase entry under 35U.S.C. § 371 of PCT Application No. PCT/IE2014/000005, filed on Mar. 18,2014, which claims priority to European Application No. 13159640.5,filed on Mar. 15, 2013, the entireties of each of which are incorporatedby reference herein.

TECHNICAL FIELD

The invention relates to a device suitable for removing matter frominside the lumen and the wall of a body lumen. In particular, theinvention relates to a thrombectomy device for removing thrombus fromthe walls of a vein or artery of a human.

BACKGROUND TO THE INVENTION

There have been many methods and devices to extract a blockage fromvessels. Thrombectomy devices exist that macerate and extract the clotrather than pulling out the clot intact. The followings are some of therelated patents.

U.S. Pat. No. 5,972,019 introduces an embolism treatment device having acore element and a cage. The cage may include an expandable braid whichis rotatably attached to the core element and can be opened to separatethe clot from the vessel wall or be expanded beyond the clot to pull itout. The core element has a rotatable part which is non removable fromthe cage.

U.S. Pat. No. 6,066,158 discloses an embolectomy device having a corewire element and a spiral collector to collect the embolism. The devicemay also have an actuator to allow expansion of the cage after delivery.

U.S. Pat. No. 5,795,322 presents a device for reducing the size ofthrombus and removing it from the vessel. The device is a tube-likecatheter with a filter formed from longitudinal strip-shape of thecatheter. The filter opens when the distal and the proximal sided arepushed towards each other respectively. The device comprises a jet flowand lumen to extract the clot.

U.S. Pat. No. 6,660,014 presents a catheter for removing occlusivematerial from vessel lumen. The catheter comprises a radially expandablepositioning cage and a radially expandable macerator within the cage.The diameter of the cage is adjustable with predetermined unconstraineddiameter. U.S. Pat. No. 6,454,775 discloses an expansible macerator.

Patent application US 2006/0229645 presents a radially expansible cagefor the removal of hardened and aged thrombus from the vessel wall. Thecage opening and closing is controlled at the proximal/user end bymoving the cage ends closer together or further apart; this is doneeither manually, or with a threaded tube to define the radial expansionof the cage.

U.S. Pat. No. 6,383,205 presents a mechanism including a double filterdevice to extract the clot with minimum risk of embolism.

U.S. Pat. No. 6,616,679 is a vascular device for emboli and thrombusremoval. It includes a blood permeable sac which collects the emboli andcan be collapsed. This is a fast way to extract small emboli but forlarge clot the sac need to be extremely long.

In U.S. Pat. No. 6,652,548 a thrombectomy device has been claimed. Thecatheter based device comprises shearing members located at the distalends of the catheter and the inner shearing member is rotatable.

U.S. Pat. Nos. 6,656,203, 7,083,633, 7,014,647, 6,558,405,EP1310219A3EP1310219B1, 20070173883, U.S. Pat. Nos. 6,179,859, 7,922,741and US20110125181 are examples of different structures for embolicfilters. The filter may be placed in the vessel prior to an operationsuch as stenting or PTCA. After the operation, the filter is collapsedand taken out of the body. Neither of the filters are suitable for largetapered veins with thrombosis. Because filters are not designed to bemoved along vessels after deployment, this makes it difficult to removelong thrombus. The existing devices and methods described above do nothave a high performance in harvesting large volumes of thrombus and alsothrombus in large and/or tapered and/or branched vessels. Limitationsassociated with these devices include procedural duration and thrombusremoval efficiency.

It is an object of the invention to overcome at least one of theabove-referenced problems.

STATEMENTS OF INVENTION

Broadly, the invention provides a device suitable for use in a bodylumen comprising an elongated control member and a radially expansiblemember (i.e. a cage, funnel, or a ring) disposed at or adjacent to adistal end of the elongated control arm and that is adjustable between acontracted orientation and an expanded (deployed) orientation. Theradially expansible member is adapted to remove matter (i.e. thrombus)from the walls of a body lumen (i.e. veins, arteries or other lumenssuch as the urethra), for example scrape thrombus from vessel walls,collect matter removed from the walls of a lumen, and optionally both,when in a deployed orientation. The control member comprises two arms,one of which is connected to or adjacent to a proximal end of theradially expansible member and the other of which is connected to oradjacent to a distal end of the radially expansible member. Movement ofone of the arms relative to the other effects adjustment of the diameteror radial strength of the radially expansible member, for exampleadjustment of the diameter from a contracted orientation to an expanded(deployed) orientation, or adjustment of the radial force from a firstforce to a greater force. The movement is preferably longtitudinalmovement. The device additionally includes a control mechanism that isideally operatively connected to both arms and provides resistance tomovement of one of the arms relative to the other. The control mechanismmay comprise biasing means for biasing the radially expansible memberinto, or in the direction of, an expanded or contracted orientation(FIG. 11), it may include brake means which clamp the two arms in oneorientation with a certain force such that movement of one of the armsrelative to the other only occurs when a specific predetermined force isapplied to the radially expansible member (FIG. 9), or it may comprise acombination of biasing means and brake means (FIG. 12).

A device of the invention is ideally suited for use in tapering lumenswith obstructions such as valves where movement of the cage in adeployed shape along the lumen requires the diameter of the cage tochange. When the lumen is tapering inwardly (in the direction of travelof the cage), the control mechanism exerts a force on the radiallyexpansible member resisting contraction of the radially expansiblemember (by biasing the radially expansible member into an expandedorientation or by clamping the two arms in a specific disposition) untilthe force exerted on the radially expansible member by the lumen exceedsthe total resistance force including that exerted by the resistancemechanism at which point the diameter of the radially expansible memberwill reduce. This means that the radially expansible member can be movedalong the walls of the lumen exerting radial force against the walls,thereby effecting a scraping/collecting action.

Likewise, when the tube is tapering outwardly (in the direction oftravel of the cage), the resistance mechanism comprises biasing meansthat exerts a force on the cage by biasing the cage into an expandedorientation. This means that cage will scrape along the walls of thevasculature exerting radial force against the walls, thereby effecting ascraping action along the outwardly tapering walls.

According to the invention, there is provided a device suitable for usein a body lumen and comprising:

-   -   an elongated control member having a distal and a proximal end,        and a radially expansible member disposed at or near the distal        end and adapted for collection and/or shearing of matter from a        wall of the body lumen,    -   the radially expansible member having a proximal end and a        distal end and being adjustable between a contracted orientation        and an expanded orientation,    -   the elongated control member comprising a proximal arm connected        to the radially expansible member and a distal arm connected to        the radially expansible member distally of the proximal arm        connection such that movement of one arm relative to the other        arm effects adjustment of the diameter and/or radial strength of        the radially expansible member,        the device being characterised in that it comprises a control        mechanism operatively connected to both arms and adapted to        provide resistance to the movement of one arm relative to the        other.

The distal arm is generally connected to the radially expansible memberdistally of the proximal arm connection. Thus, the distal arm may beconnected at or adjacent to the distal end of the radially expansiblemember, and the proximal arm may be connected to the radially expansiblemember at a point between the distal arm connection and the proximal endof the cage.

Preferably, the radially expansible member is a cage, although otherradially expansible members such as, for example, expansible rings,funnels are envisaged. The radially expansible member may be formed fromone, two, or more struts, which may be arranged in a helical arrangementto form the cage.

The distal or proximal arm may be, for example, a wire or a tube. In oneembodiment, one of the arms is a tube (for example the proximal arm) andthe other arm (for example the distal arm) is a wire, in which the wireis suitably disposed within a lumen in the tube. Suitably, the distaland proximal arms are co-extensive along most of their length (forexample they are coextensive up to the cage). The control membercomprising the two arms may be disposed within a tube, typically acatheter tube. In a preferred embodiment, the proximal arm is tubularand the distal arm is disposed within the proximal arm. Preferably, thedistal arm is tubular (so as to facilitate the device being deliveredover a guidewire).

Typically, the control mechanism comprises biasing means adapted to biasthe radially expansible member into, or in the direction of, theexpanded or contacted orientation. Ideally, the control mechanismcomprises biasing means adapted to bias the cage into, or in thedirection of, the expanded orientation.

Suitably, the control mechanism comprises brake means adapted to resistmovement of one arm relative to the other arm. One embodiment of a brakemeans is a friction screw, typically an adjustable friction screw.Preferably, the control mechanism is adjustable so that the level ofresistance to movement can be adjusted.

In one embodiment, the control mechanism comprises biasing means adaptedto bias the radially expansible member into, or in the direction of, theexpanded or contacted orientation and brake means adapted to resistmovement of one arm relative to the other arm, for example brake meansadapted to prevent expansion or retraction of the radially expansiblemember.

Suitably, the control mechanism comprises a first part connected to oneof the arms, a second part connected to the other of the arms andmovable relative to the first part, and force controlled resistancemeans for resisting movement of the first part relative to the secondpart. The force controlled resistance means may be biasing means adaptedto bias the cage into, or in the direction of, the expanded or contactedorientation, and/or brake means adapted to resist movement of theradially expansible member or movement or one arm relative to the otherarm, typically both.

In this specification, the term “force controlled” as applied to theresistance mechanism should be understood to mean that the diameter ofthe radially expansible member is not predetermined or controlled, butis dependent on the force applied.

In one preferred embodiment, the invention provides a device suitablefor use in a body lumen and comprising:

-   -   an elongated control member having a distal and a proximal end,        and a radially expansible member disposed at or near the distal        end and adapted for collection and/or shearing of matter from a        wall of the body lumen,    -   the radially expansible member having a proximal end and a        distal end and being adjustable between a contracted orientation        and an expanded orientation,    -   the elongated control member comprising a proximal arm connected        to the radially expansible member and a tubular distal arm        connected to the radially expansible member distally of the        proximal arm connection such that movement of one arm relative        to the other arm effects adjustment of the diameter and/or        radial strength of the radially expansible member,    -   a control mechanism operatively connected to both arms and        adapted to provide resistance to the movement of one arm        relative to the other, in which the control mechanism comprises        a first part connected to one of the arms, a second part        connected to the other of the arms that is movable relative to        the first part, and force controlled resistance means for        resisting movement of the first part relative to the second        part,        characterised in that the force controlled resistance means        comprises (a) biasing means for biasing the radially expansible        member into the expanded orientation, or (b) a brake means        adapted to resist movement of one of the first and second parts        relative to the other of the first and second parts.

In another embodiment, the invention provides a device suitable for usein a body lumen and comprising:

-   -   an elongated control member having a distal and a proximal end,        and a radially expansible member disposed at or near the distal        end and adapted for collection and/or shearing of matter from a        wall of the body lumen,    -   the radially expansible member having a proximal end and a        distal end and being adjustable between a contracted orientation        and an expanded orientation,    -   a thrombus extractor, at least a part of which is preferably        disposed within the radially expansible member    -   the elongated control member comprising a proximal arm connected        to the radially expansible member and a distal arm connected to        the radially expansible member distally of the proximal arm        connection such that movement of one arm relative to the other        arm effects adjustment of the diameter and/or radial strength of        the radially expansible member,    -   a control mechanism operatively connected to both arms and        adapted to provide resistance to the movement of one arm        relative to the other, in which the control mechanism comprises        a first part connected to one of the arms, a second part        connected to the other of the arms that is movable relative to        the fixed first part, and force controlled resistance means for        resisting movement of the first part relative to the second        part,        characterised in that the force controlled resistance means        comprises (a) biasing means for biasing the radially expansible        member into the expanded orientation, or (b) a brake means        adapted to resist movement of one of the first and second parts        relative to the other of the first and second parts.

Typically, the force controlled resistance means comprises biasingmeans, for example a resiliently deformable or displacable member suchas for example a spring or a pneumatic or hydraulic member, generallydisposed between the first and second parts of the control mechanism.The spring may be any type of spring, for example a compression,tension, flat, constant force, or adjustable constant spring.

In one embodiment, the force controlled resistance means comprisesbiasing means, for example a resiliently deformable member disposedbetween the first and second parts of the resistance mechanism, and abrake means adapted or configured to resist movement of one of the firstand second parts relative to the other of the first and second parts.

The control mechanism may be disposed at any point along the device, forexample proximal to the radially expansible member, distal to theradially expansible member, or adjacent to or within the radiallyexpansible member. In a preferred embodiment, the control mechanism isdisposed at a proximal end of the catheter (for example, on the handle)such that, in use, it is exposed proud of the body.

In a preferred embodiment of the invention, the first part of thecontrol mechanism is connected to the proximal end of the radiallyexpansible member by means of the proximal arm, and the adjustablesecond part of the control mechanism is attached to the distal end ofthe radially expansible member by means of the distal arm. Thus, thedistal arm typically passes through the cage.

Preferably, the proximal arm is a tube comprising a lumen and the distalarm is disposed within the lumen of the first arm, typically coaxiallywith the first arm. Preferably, the distal arm is a tube, ideallyadapted for receipt of a guidewire.

Movement of one arm relative to the other arm effects adjustment of thediameter and/or radial strength of the radially expansible member.Preferably, the movement is longtitudinal movement, although othermovement is envisaged, for example lateral, radial, circumferentialrotational or combinations thereof.

In one embodiment, the brake means comprises a friction screw fixed toone of the parts of the control means and adjustable to engage the otherpart of the control means (or the arm that is operably connected to theother part). Preferably, the friction screw is fixed to the second part,for example a movable stop forming part of the second part, and isadjustable to engage the first part or the control means or the distalarm that is operable connected to the first part.

In one embodiment of the control mechanism, the first part comprises abarrel, and the second part is adapted for sliding movement within thebarrel, wherein the resistance means comprises a friction screw,preferably an adjustable friction screw, disposed on the barrel andadapted for engagement with the second part. Suitably, the resistancemeans additionally comprises biasing means suitably adapted to bias thecage into, or in the direction of, the expanded orientation.

Typically, the control mechanism is disposed proximally of the radiallyexpansible member such that in use it is located outside of the body.Suitably, the first part is operably connected to the proximal arm andcomprises a guide path, and the second part is operably connected to thedistal arm and is associated with the first part for movement along theguide path, and wherein the force controlled resistance means comprisesa resiliently deformable member disposed along the guide path betweenthe first and second parts. Preferably, the first part comprises abarrel and a second part comprises a block configured for sliding andcontrolled movement within the barrel.

Typically, the first part comprises a movable stop which is movable tovary the length of the guide path and/or the resiliently deformablemember.

Suitably, the brake means comprises a friction screw operably connectedto the movable stop and configured for adjustable engagement with thedistal arm.

Suitably, the control mechanism is disposed within the radiallyexpansible member and comprises a first part connected to the distalarm, a second part connected to the proximal arm, and a helical springoperatively connected to the first and second parts and configured toprovide force controlled resistance to movement of the first and secondparts together.

Preferably, the radially expansible member comprises a cage. Suitably,the cage comprises a proximal portion having apertures for receipt ofthrombus into the cage, and a distal portion having a fine mesh forcapturing thrombus, in which the cage optionally comprises a cut tube.Alternatively, the cage comprises a distal portion having apertures forreceipt of thrombus into the cage, and a proximal portion having a finemesh for capturing thrombus, in which the cage optionally comprises acut tube.

Suitably, the control mechanism is disposed distally of the radiallyexpansible member. Suitably, the control mechanism comprises aresiliently deformable member (i.e a spring) having a distal end (firstpart) operably connected to the distal arm and a proximal end (secondpart) operably connected to a distal end of the radially expansiblemember, and wherein the distal end of the distal arm is operablyconnected to the distal end of the radially expansible member by meansof the resiliently deformable member.

Preferably, the device comprises an extractor at least a part of whichis disposed within the radially expansible member. Suitably, theextractor comprises holes or apertures dimensioned to allow blood, butprevent thrombus, pass out of the extractor.

Suitably, the extractor comprises a helical formation adapted to rotate.The rotation is adapted to remove thrombus from the radially expansiblemember or optionally deliver agents into the body lumen, for example athrombolytic agent. The helical formation may comprises a single, doubleor triple helical formation. Typically, the pitch of the helix on thehelical formation is configured to squeeze blood from thrombus duringuse.

Typically, the helical formation is disposed within an extractor tube.Ideally, a portion of the helical formation within the radiallyexpansible member is exposed by means of, for example, one or morewindows or cut-away portions.

Suitably, a leading edge of the extractor tube comprises a cutting edge.Preferably, the helical formation comprises a cutting edge, ideallydisposed at or adjacent a distal end of the helical formation. In oneembodiment, a leading edge of the extractor tube comprises a cuttingedge and the extractor comprises an aspirator tube.

In one embodiment, the thrombus extractor is an aspirator tube.

Typically, the force controlled resistance means is self-adjusting. Inthis specification, the term “self adjusting” as applied to the forcecontrolled resistance means should be understood to mean that theresistance means adjusts itself without any user input other than theactions of the user to move the device along a vessel.

Typically, the elongated control member is contained within a tubularsheath. Ideally the tubular sheath extends along all or most of thelength of the control member. Suitably, the longtitudinal position ofthe sheath is adjustable. Suitably, the tubular sheath can be adjustedto cover the radially expansible member and maintain the radiallyexpansible member in a contracted orientation.

Typically, the tubular sheath comprises a plurality of holes forperfusion of a liquid.

Suitably, the device comprises a liquid administration lumen configuredto deliver a liquid into the body. Preferably, the liquid administrationlumen comprises a lumen formed within the distal arm, between the distalarm and proximal arm, and between the proximal arm and an externalsheath. Ideally, the device comprises an injection port for delivery ofliquid into the liquid administration lumen. In a preferred embodiment,the invention provides a device suitable for use in a body lumen andcomprising:

-   -   an elongated control member having a distal and a proximal end,        and a radially expansible member disposed at or near the distal        end and adapted for collection and/or shearing of matter from a        wall of the body lumen,    -   the radially expansible member having a proximal end and a        distal end and being adjustable between a contracted orientation        and an expanded orientation,    -   the elongated control member comprising a proximal arm connected        to the radially expansible member and a distal arm connected to        the radially expansible member distally of the proximal arm        connection such that movement of one arm relative to the other        arm effects adjustment of the diameter or radial strength of the        radially expansible member,        the device being characterised in that it comprises biasing        means for biasing the radially expansible member into, or in the        direction of, an expanded orientation.

In another embodiment, the invention provides a device suitable for usein a body lumen and comprising:

-   -   an elongated control member having a distal and a proximal end,        and a radially expansible member disposed at or near the distal        end and adapted for collection and/or shearing of matter from a        wall of the body lumen,    -   the radially expansible member having a proximal end and a        distal end and being adjustable between a contracted orientation        and an expanded orientation,    -   the elongated control member comprising a proximal arm connected        to the radially expansible member and a distal arm connected to        the radially expansible member distally of the proximal arm        connection such that movement of one arm relative to the other        arm effects adjustment of the diameter or radial strength of the        radially expansible member,        the device being characterised in that it comprises biasing        means for biasing the radially expansible member into, or in the        direction of, an expanded orientation and brake means brake        means adapted to resist movement of one arm relative to the        other arm.

In another embodiment, the invention provides a device suitable for usein a body lumen and comprising:

-   -   an elongated control member having a distal and a proximal end,        and a radially expansible member disposed at or near the distal        end and adapted for collection and/or shearing of matter from a        wall of the body lumen,    -   the radially expansible member having a proximal end and a        distal end and being adjustable between a contracted orientation        and an expanded orientation,    -   the elongated control member comprising a proximal arm connected        to the radially expansible member and a distal arm connected to        the radially expansible member distally of the proximal arm        connection such that movement of one arm relative to the other        arm effects adjustment of the diameter or radial strength of the        radially expansible member,        the device being characterised in that it comprises a resistance        mechanism comprising a fixed first part connected to one of the        arms, a second part connected to the other of the arms and        movable relative to the fixed first part, and resistance means        for resisting movement of the first part relative to the second        part, in which the resistance means optionally comprises biasing        means adapted to bias the cage into the expanded or contacted        orientation or brake means adapted to prevent expansion of the        cage.

In one embodiment, the radially expansible member is a cage. Typically,the cage is a filtering cage (i.e. it is adapted to collect or filterthrombus from blood that passes through the cage). In anotherembodiment, the cage is a shearing cage (i.e. a cage adapted to shear orscrape thrombus from a wall of the vasculature). In a preferredembodiment, the cage is both a shearing and filtering cage. Suitably,the cage has a proximal end that is at least partially open (for receiptof thrombus). The cage may comprise a braided material, for example abraided wire, or it may comprise a cut tube, for example a cut tube(i.e. Polymeric, metal such as stainless steel Nitinol or cobaltchromium, or ceramic; or a combination of these materials) or a lasercut tube, or it may comprise a braided material and a cut tube. Whenformed from a braided material, the density of the braid may be greatertowards the distal end of the cage that the proximal end of the cage. Ina preferred embodiment, the cage is formed from a shape memory materialsuch as Nitinol. Preferably, the cage has an at least partially openproximal end and tapers inwardly towards its distal end.

In one embodiment, the cage comprises a distal section having a finemesh, and an intermediate section having large apertures. Thus, the finemesh is suited for filtering/capturing thrombus, and the large aperturesadapted for allowing passage into the cage of thrombus. Typically, thecage is cut from a tube, suitably a polymeric or metal tube.

In one embodiment, the cage comprises a cutting element disposedcircumferentially around the cage. This may be a wire, or a cuttingedge. Typically, at least a part of the cutting element is exposed proudof the cage. Suitably, at least a part of the cutting element isdisposed within the cage. Typically, the cutting element is disposedwith respect to the cage such that the cutting element expands andcontracts with the expansion and contraction of the cage, respectively.

In one embodiment, the invention provides a device suitable for use in abody lumen and comprising:

-   -   an elongated control member having a distal and a proximal end,        and a cage disposed at or near the distal end and adapted for        collection and/or shearing of matter from a wall of the body        lumen,    -   the radially expansible member having a proximal end and a        distal end and being adjustable between a contracted orientation        and an expanded orientation,    -   the elongated control member comprising a proximal arm connected        to the radially expansible member and a distal arm connected to        the radially expansible member distally of the proximal arm        connection such that movement of one arm relative to the other        arm effects adjustment of the diameter or radial strength of the        radially expansible member        the device being characterised in that the cage comprises a        distal section having a fine mesh for capturing thrombus,        optionally a proximal section having a coarse mesh adapted for        crimping attachment to the proximal arm, and an intermediate        section having apertures dimensioned to allow passage of        thrombus into the cage.

In another embodiment, the invention provides a device suitable for usein a body lumen and comprising:

-   -   an elongated control member having a distal and a proximal end,        and a cage disposed at or near the distal end and adapted for        collection and/or shearing of matter from a wall of the body        lumen,    -   the cage having a proximal end and a distal end and being        adjustable between a contracted orientation and an expanded        orientation,    -   the elongated control member comprising a proximal arm connected        to the radially expansible member and a distal arm connected to        the radially expansible member distally of the proximal arm        connection such that movement of one arm relative to the other        arm effects adjustment of the diameter or radial strength of the        radially expansible member,        the device being characterised in that the cage has an at least        partially open proximal end and tapers inwardly towards its        distal end, and wherein a helical extractor is optionally        disposed within the cage towards a distal end of the cage.

In one embodiment, the invention provides a device suitable for use in abody lumen and comprising:

-   -   an elongated control member having a distal and a proximal end,        and a cage disposed at or near the distal end and adapted for        collection and/or shearing of matter from a wall of the body        lumen,    -   the cage having a proximal end and a distal end and being        adjustable between a contracted orientation and an expanded        orientation,    -   the elongated control member comprising a proximal arm connected        to the radially expansible member and a distal arm connected to        the radially expansible member distally of the proximal arm        connection such that movement of one arm relative to the other        arm effects adjustment of the diameter or radial strength of the        radially expansible member,        the device being characterised in that the cage comprises a        cutting or seperation element disposed circumferentially around        the cage.

Preferably, the device of the invention comprises an extractor formatter (i.e. debris such as thrombus) at least a part of which ispreferably disposed within the radially expansible member. The extractormay comprise either aspiration, a helical formation adapted to rotateand remove thrombus from the radially expansible member, or acombination of both. The helical formation may comprise a screw orauger, that is preferably arranged co-axially about the second (distal)arm, but optionally may be arranged eccentrically to the radiallyexpansible member axis. Alternatively, the helical formation maycomprise a helical wire or the like arranged, for example, around thedistal arm and adapted to rotate. Preferably, the helical formation isdisposed within an extractor tube, wherein a distal end of the helicalformation that is disposed within the cage is exposed proud of theextractor tube (i.e. the tube may be cut-away leaving a part of thehelical formation within the radially expansible member exposed. In oneembodiment of the invention, the extractor comprises a wire arrangedhelically about the distal arm for rotation about the arm, and anextractor tube, wherein the helical wire and distal arm are disposedwithin the extractor tube with a portion of the distal end of thehelical wire exposed proud of the extractor tube. Suitably, theextractor tube comprises a window disposed within the cage, typicallydisposed towards the distal end of the cage. Preferably, a leading edgeof the extractor tube comprises a sharp or cutting edge.

In the device of the invention, the proximal arm is generally connectedat or adjacent to the proximal end of the radially expansible member.Typically, the distal arm is generally connected at or adjacent to thedistal end of the radially expansible member.

Preferably, the device is a thrombectomy device, ideally a thrombectomycatheter.

The invention also relates to a method for removing matter from a targetarea of a wall of a body lumen, for example thrombus from a wall of avein or artery, comprising a step of providing a device according to theinvention with the radially expansible member is a contractedorientation, inserting the device into the target lumen such that theradially expansible member is positioned distally of the target area ofthe wall, adjusting the radially expansible member from a contractedorientation to an expanded (deployed) orientation, and withdrawing theradially expansible member along the lumen such that the radiallyexpansible member scrapes some/all matter from the target area of thewall of the lumen.

The invention also provides a method of removing thrombus from a bloodvessel comprising the steps of placing the device of the invention in ablood vessel, and moving the device along the blood vessel. Typically,the device is moved along the blood vessel in an inwardly taperingdirection or an outwardly tapering direction. Suitably, the blood vesselis a vein, typically a large vein.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be more clearly understood from the followingdescription of some embodiments thereof, given by way of example only,in which:

FIG. 1. Shows a braided cage in its expanded configuration, with afiltered end (201) and an open end (202).

FIG. 2. An example of a cage made from laser cut Nitinol. The distalside is solid tube and the proximal side is a closed mesh to fit overthe proximal arm tube.

FIG. 3. An example of a laser cut cage after expansion. Thecircumferential elements act as filter and separate the thrombus fromthe vessel wall.

FIG. 4. Cage with cutting element external to the cage.

FIG. 5. Cage with cutting element internal to the cage.

FIG. 6. Cage with cutting element as part of the cage.

FIG. 7. The perimeter of the cage may be tapered at an angle.

FIGS. 8A and 8B. Schematic of the cage and control mechanism, operatedusing a friction screw.

FIG. 9. Schematic of the cage and control mechanism, operated using afriction screw.

FIG. 10. Schematic of the cage and control mechanism, operated using afriction screw and a spring.

FIGS. 11A and 11B. Schematic of the cage and control mechanism, operatedusing a spring, and a movable stop.

FIG. 12. Schematic of the cage and control mechanism, operated using aflat spring.

FIG. 13. Schematic of the cage and control mechanism, operated using aflat spring.

FIG. 14. Schematic of the control mechanism, operated using a flatspring.

FIG. 15. The extractor is made of a wire wrapped around a tube. Ittransports and macerates the thrombus.

FIG. 16. The wire may be displaced above the tube surface.

FIG. 17. The proximal arm may act as the outer tube of the extractionmechanism and provide a passage way to let material from the bloodvessel into the lumen of the macerator.

FIGS. 18A and 18B. The proximal arm of extractor with cutting edge andlarger extraction path.

FIGS. 19A and 19B. The proximal arm of extractor may have more than oneleading edge.

FIG. 20. Image of the macerator with a rotating tip/cutting edge. Thetip rotates with the helical formation.

FIG. 21. Shows the cage in its open configuration. The passagewayprovided by the proximal arm, may be located inside the cage.

FIG. 22. The extractor may be eccentric to the centreline of the cage.

FIG. 23. The tip of the extractor may be eccentric and positioned awayfrom the centreline of the cage.

FIG. 24. Section view—the extractor may contain a region with a shorterpitch. This may compress the debris being extracted and allow fluid toflow back through the cavities and into the vessel.

FIG. 25. Section view—Combination of the cage and the extractor. Thecage is opened and closed by the relative movement of the proximal anddistal arms. The rotating extractor rotates over the distal arm andwithin the proximal arm. A sheath can run over the device to ensure thecage is closed during delivery and retrieval.

FIG. 26. Section view—The distal end of the device showing an embodimentof the cage with the extractor tube acting also as the distal arm. Asthe distal arm moves proximally, the cage opens. As the distal arm movesdistally, the cage closes.

FIG. 27. Section view—The tip of the device. In this embodiment theextractor tube also acts at the distal arm. The extractor tube rotatesat high speed while cage connector does not rotate. The bearingfacilitates this relative movement.

FIG. 28. Schematic of a device of the invention with a control mechanismlocated within the cage.

FIG. 29. Schematic of a device of the invention with a control mechanismlocated distally of the cage.

FIG. 30. Schematic of the device having a sheath covering the elongatedcontrol member and adjustable to cover the cage.

FIG. 31. Schematic of the device of the invention showing howthrombolytic agents may be infused through the extractor.

FIG. 32. Schematic of the device of the invention showing howthrombolytic agents may be infused between the extractor and the sheath

FIG. 33. Schematic of the device of the invention showing howthrombolytic agents may be infused through holes or perforations formedin the sheath.

FIG. 34. Schematic of a radially expansible member formed from a singlestrut.

FIGS. 35A and 35B. Schematic of a radially expansible member formed fromtwo struts.

FIG. 36. An example of the radially expansible member made from a seriesof wires, and fused or twisted for connection (shown as a flat pattern).

FIG. 37. An example of a braided expansible member with the wirestwisted at the intersections to limit the movement of the wires withrespect to each other (shown as a flat pattern).

FIG. 38. An example of a braid configuration for the creation of abraided radially expansible member, with twisted wires (for struts) andfused ends (shown as a flat pattern).

FIG. 39. An example of a braid configuration for the creation of abraided radially expansible member, with twisted wires to create struts.

DETAILED DESCRIPTION OF THE INVENTION Cage and Filter

The cage can be made in many different ways, such as from a braid, aseries of wires, laser cut tubes or a combination of them. The cage alsomay act as a filter or be a structure for the filter at the distal part.The cage can be made of different materials such as, but not limited to,polymeric, metal such as stainless steel Nitinol or cobalt chromium, orceramic; or a combination of these materials. The proximal side of thecage is generally open and allows thrombus into the cage. The distalpart of the cage is suitably constrained onto a tube or wire with smalldiameter and the proximal part of the cage is connected to a tube withlarger diameter. A sheath may cover the entire device at delivery and atretrieval.

A connector, which can be a wire or tube and connects the distal end ofthe cage to user or controls the distal movement of the cage, is calledthe distal arm. Another connector, which can be a wire or tube andconnects the proximal end of the cage to user, is called the proximalarm.

Once the cage is assembled and opened, section 202 provides a passagewayfor thrombus into the cage, while section 201 prevents large thrombuspassing the cage (1).

In FIGS. 2 and 3, an example of a cage which has been laser cut fromNitinol tube is shown. The laser cuts have the same feature as thebraided mesh. It provides a passageway on the proximal side and acts asfilter on the distal side. It may also carry circumferential elementsfor cutting through thrombus and separating thrombus from the wall.

By pushing the proximal and distal ends of the cage axially towards eachother the diameter of the cage and its radial force may increase. Bypulling the sides away from each other the diameter and the radial forceof the cage may decrease.

Relative movement of the distal and proximal arms controls the distancebetween the distal and proximal sides of the cage; this adjusts thediameter and radial strength of the cage. If the distal arm is fixed andthe proximal arm is pulled proximally by the user, the diameter of thecage becomes smaller. If the proximal arm is fixed and the distal arm isbeing pulled, the diameter of the cage increases.

The cage may also have a circumferential cutting element forremoving/scraping thrombus from the vessel wall. This may be containedaround or within the cage and may be composed of a round wire, flatwire, blade or a combination of these. FIG. 4 shows the cage with a flatwire attached the outside of the cage; the wire can scrape thrombus fromthe vessel wall. FIG. 5 shows the cutting element internal to the cage,while FIG. 6 shows the cutting element of the cage as one part (in thiscase from a laser cut tube). The cutting/scraping element may also betapered at an angle (FIG. 7).

A Cage with Self Adjustable Diameter Control Mechanism

In the case of treating a tapered vessel, the cage diameter should beadjustable while it is pulled along the lumen. Also in the case ofobstruction such as vascular valve it is desirable that the device beable to manoeuvre through it. Therefore a mechanism which can controlthe diameter of the cage by changing the resistance force is desirable.Presented here is a mechanism to control the diameter of the cage basedon resistance forces.

As the cage moves through a reducing tapered vessel (pulling theproximal arm), the vessel exerts a force on the cage. When the forcefrom the vessel exceeds the total force including the preset force fromthe resistance mechanism (set by the user), the distal arm movesdistally relative to the proximal arm; this closes the cage. The nextsection includes some embodiments of the self-adjustment mechanisms.

The control mechanism may contain friction elements, springs,pneumatics, hydraulics, simple weight, or a combination of theseelements.

Resistance Mechanism: Sliding

In this embodiment of the invention (FIGS. 8A, 8B, and 9), the cage (3)is made from a laser cut self-expanding tube. The cage opens when 1 band 2 b move closer together, and closes when 1 b and 2 b move apart.The mechanism for controlling the diameter and force exerted by the cageon the vessel wall is the basis for the current invention.

The device, as shown in FIGS. 8A and 8B, consists of a cage (3) whichhas a distal end (1 b) and a proximal end (2 b), a distal arm (1), aproximal arm (2), and a handle. The control mechanism is comprised inthe handle, and comprises a first part in the form of a housing (2 a)having a guidance path, a second part in the form of a sliding block (1a) configured for sliding movement along the guidance path of thehousing (2 a). Force controlled resistance means is provided in the formof a brake adapted to resist movement of one or the arms relative to theother. In this embodiment, the brake comprises a friction screw (4)mounted on the housing (2 a) and adjustable to apply a compression forceagainst the sliding block (1 a) to provide resistance to movement of onearm relative to the other, and in the case of the device being passedalong a vessel that tapers inwardly, resistance to the compression ofthe cage which has the effect of keeping the periphery of the cage incontact with the vessel wall.

The process begins in an expanded state in the vessel as shown in FIG.8A. The opening and closing of the cage is governed by the relativemovement of the sliding block (1 a) to the handle (2 a). As the cage ispulled by the handle through an obstruction or the tapered section ofthe vessel (5), force from the vessel wall is exerted to the cage. Thisforce is transferred to the sliding block (1 a). If the force applied tothe block 1 a is larger than the preset friction force, then the block 1a slides forward from its position in FIG. 8A to its position in FIG.8B. This allows the cage to conform to the shape of the narrower vessel.The force exerted by the cage on the vessel is therefore dictated inpart by the ease of movement of the sliding block relative to thehandle; this is controlled by the friction screw.

Resistance Mechanism: Sliding and Spring

FIGS. 11A and 11B show an alternative embodiment of the resistancemechanism in which parts described with reference to FIG. 10 areassigned the same reference numerals. In this embodiment, a compressionspring (6) is disposed along the guide path between the housing (2 a)and the sliding block (1 a). The housing (2 a) is connected to theproximal arm (2) and the block (1 a) is connected to the distal arm (1).Thus, compression of the cage (3) into a contracted orientation causesthe distal arm (1) to extend, causing compression of the spring. In thismanner, the cage is biased into an expanded orientation when it is beingpassed along a vessel that is narrowing, thereby maintaining contactbetween the cage and the vessel wall. A friction screw (4) is mounted onthe housing (2 a) and is adjustable to apply a compression force againstthe block (1 a) and thereby provides further resistance to movement ofone arm relative to the other, and in the case of the device beingpassed along a vessel that tapers inwardly, again provides resistance tothe compression of the cage which has the effect of keeping theperiphery of the cage in contact with the vessel wall.

FIGS. 11A and 11B show an alternative embodiment of the resistancemechanism in which parts described with reference to FIGS. 8 to 10 areassigned the same reference numerals. In this embodiment, the selfadjusting mechanism comprises a movable stop (7) that is movable toadjust the length of the guidance path and, thus, the degree ofcompression of the spring. Thus, the force that the spring applies canbe varied by changing the position of the movable stop (7) along theguidance path.

Resistance Mechanism: Spring With Adjustable Spring Constant

In this embodiment the distal arm (1) is attached to a flat spring (22).The other side of the spring (22) is fixed respect to proximal arm (2)through a solid handle (20). Since the spring constant of a flat springchanges with its length, a mechanism for adjusting its length (21) canslide over the spring to control its deformation. When the sliding part(21) is down (FIG. 12) the spring constant is the lowest which means itallows higher displacement of inner tube (1) at a lower force. When thesliding tube (21) rises (FIG. 13), the spring constant (22) increaseswhich allows less displacement of inner tube (1). This effectivelyreduces the cage diameter (3). FIG. 14 shows a 3D representation of themechanism.

The Extraction Mechanism

The extraction system may consist of suction, or a rotating tube/wirewith a means of transformation and/or maceration on the outer surface;the extraction system may also contain a combination of thesemechanisms. The rotating extractor may be manufactured from one part ormade from several attachments. For example, the extraction mechanism maycomprise a wire (42) wrapped around an extraction core tube (43) (FIG.15). This tube may be placed over the distal arm (1) of the cage andinside the proximal arm (2). Alternatively, the distal arm may be usedas the extraction core tube. The distal side of the extraction core tubemay be close to the distal end of the proximal arm (2). As theextraction tube turns at high speed thrombus is forced proximallybetween the extraction tube and the proximal arm. The distal end of theextraction mechanism may be located inside the cage (FIG. 1).

The wire may have varying cross sections along the device for differentmeans; from circular, rectangular or triangular cross sections. The wirecan be from different materials such as stainless steel, Nitinol, orpolymers. Once the wire is wrapped around the tube, it might becompletely fit around the tube (41) or be partially fit at a distance(43) from the rotating tube (41) surface (FIG. 16).

The proximal arm may also contain a side window (FIG. 17) to improveaccess of the extractor to thrombus. The extractor may also be formedfrom one machined part rather than a wire wrapped around a tube. Therotating extractor will likely contain sharp cutting edges at its distalend to break up matter prior to extracting it. The non-rotating proximalarm may also have a leading edge/cutting element (FIGS. 18A and 18B)which helps to break down thrombus, while also increasing the size ofthe path at the entrance of the extractor. The proximal arm may havemore than one leading edge/cutting element to break down matter; FIGS.19A, and 19B show the proximal arm with two leading edges. The leadingedge/cutting element may form part of the proximal arm (as shown) oralternatively be a separate part attached to the non-rotating proximalarm. The extractor may also contain an additional port at the proximalend where suction can be added to enhance thrombus extraction, and toattract thrombus towards the extractor. FIG. 20 shows an embodiment inwhich the rotating tip and helical wire are attached to the distal armfor rotation therewith. FIG. 21 shows the extractor with the cage. Theextractor may also be eccentric to the centre of the cage; FIG. 22 showsthe extractor eccentric to the centre cage and adjacent to it while FIG.23 shows the tip of the cage away from the centre of the cage. In bothFIGS. 22 and 23 the extractor may be stationary or rotate around thecentreline.

The extractor may have a varied pitch along its length. One embodimentof this is shown in FIG. 24, where a section of the extractor has areduced pitch, and the non-rotating tube has a number of small holes(acting as a filter) in it. This may allow any debris to be squeezed,forcing residual fluid through the holes and into the vessel while theremaining debris continues to be extracted.

The extraction mechanism in combination with the cage may have variousfunctions along the device. In one embodiment, the extractor breaks downthe thrombi into relatively big pieces which are small enough to enterthe inlet of tube and big enough not to pass through the filter. Oncethe thrombus is inside the tube, the extractor, breaks them down intosmaller pieces, make it easier to transfer along the catheter. Then, theextraction system may have a means of extraction such as helical wire orvacuum. The matter removed will be collected in a suitable collectionmeans, for example a blood bag, or syringe or similar.

The helical formation may have a cutting edge, and which is adapted torotate with the helical formation and cut or break up thrombus forextraction. The cutting edge may be a blade ore the like, and may bedisposed at or close to an end of the helical formation. The extractortube may also have a cutting edge, and may be adapted to rotate.

Combination of the Cage and Extractor

The device contains both a cage with a self adjustment mechanism, and anextractor. FIG. 25 shows an embodiment of the distal end of the device.The device is opened and closed by the relative movement of the proximaland distal arms, while the extractor rotates over the distal arm andwithin the proximal arm. The proximal arm may also contain a window forextraction. A sheath covers the entire device during delivery andretrieval.

FIG. 26 shows another embodiment of the distal end of the device, withthe cage and extractor combined. In this embodiment, the rotatingextractor also acts at the distal arm; the relative movement of whichopens and closes the cage. A ball bearing has been included tofacilitate contact of the rotating extractor/distal arm and non-rotatingproximal arm and cage (FIG. 27).

Device With Control Mechanism Within Cage

FIG. 28 shows an embodiment of the device in which the control mechanismis disposed within the cage. In this embodiment, a control mechanism isprovided within the cage (3) and comprises a first part operablyconnected to the proximal arm (2), a second part operably connected tothe distal arm (1), and a helical spring (6) connecting the first andsecond parts. In use, as the cage passes along a vessel that is taperinginwardly, the control mechanism ensures that a force controlledresistance is applied to the cage as it contracts, thereby ensuring thatthe cage remains in contact with the walls of the vessel.

Device With Control Mechanism Mounted Distally of Cage

FIG. 29 shows an embodiment of the device in which the control mechanismis disposed distally of the cage. In this embodiment, the devicecomprises a proximal arm (2), which is connected to a proximal part (2b) of the cage and which extends through, and distally beyond, the cage,and a distal arm (1) which extends distally of the cage (3). The controlmechanism comprises a first part (block 1 b) operably connected to anend of the proximal arm, a second part operably connected to the distalarm (1), and a helical spring (6). In use, as the cage passes along avessel that is tapering inwardly, the control mechanism ensures that aforce controlled resistance is applied to the cage as it contracts,thereby ensuring that the cage remains in contact with the walls of thevessel.

Device With Outer Sheath

Specifically, FIG. 30 shows an embodiment of the device of the inventionin which a sheath (8) is provided that covers the elongated controlmember. In this embodiment, the device can be manipulated such that thecage (3) is contracted and withdrawn within the sheath, which will thuskeep it in a contracted orientation

Delivery of Liquid Agent to Vessel Lumen

The device of the invention may also be employed to deliver liquidagent, for example a thrombolytic agent which can break down thrombus,to the vessel lumen. This may be achieved in a number of different waysincluding:

-   -   The direction of rotation of the extractor screw can be changed        to infuse rather than extract.    -   Inject through the hollow distal arm.    -   Inject through a lumen between the distal arm and the extractor        tube (proximal arm) (FIG. 31)    -   Injected in between the extractor tube (proximal arm) and the        sheath (FIG. 32).    -   Injected through cavities in the sheath (FIG. 33).    -   The location of the sheath and cavities can be adjusted along        the catheter length.    -   One of, or a combination of, the above methods of infusion.        Generally, the liquid agent would be injected into the delivery        lumen, which may be any of the above. Alternatively, the liquid        agent may be delivered slowly by means of a drip feed. AS        indicated above, the liquid agent may be delivered in a number        of different ways, for example through a hollow distal arm        (which has the advantage of being capable of delivering liquid        agent distally of the cage), through a lumen formed between the        distal arm and the proximal arm (also referred to as the        extractor tube), or through a lumen formed between the proximal        arm and the outer sheath.

Design of Radially Expansible Member

FIGS. 34 to 39 describe embodiments of the radially expansible memberforming part of the device of the invention, and specifically braidconfigurations that may be employed in radially expansible members.

The invention is not limited to the embodiments hereinbefore describedwhich may be varied in construction and detail without departing fromthe spirit of the invention.

The invention claimed is:
 1. A thrombectomy device, comprising: a handleat a proximal end portion of the device; a first tube; a second tubeextending to a distal end portion of the device; a cage at the distalend portion of the device, the cage being adjustable between acontracted orientation and an expanded orientation, the cage including ascraping element formed with one or more of a round wire, a flat wire,or a blade disposed between a proximal end portion of the cage and adistal end portion of the cage, the scraping element being configured toremove matter from a body lumen when the cage is in the expandedorientation; a suction device including an opening formed in a side wallof the second tube, including a source of suction connected to theproximal end portion of the device, the suction device being configuredto apply suction towards an interior of the second tube and to anextraction passage formed between the first tube and the second tube ina radial direction; wherein the opening extends between the scrapingelement and a distal end of the device in a proximal to distaldirection; and wherein the scraping element is positioned at a widestportion of the cage.
 2. The device of claim 1, wherein the opening hasan approximately rectangular shape.
 3. The device of claim 1, furtherincluding a mechanical extractor extending within the extractionpassage.
 4. The device of claim 3, wherein the suction device isconfigured to apply suction to an interior of the second tube.
 5. Athrombectomy device, comprising: a proximal end portion; a distal endportion; a radially-expandable cage at the distal end portion, the cageincluding struts forming a plurality of proximal openings and aplurality of distal openings, at least one of the proximal openingsbeing larger than one or more of the distal openings; a scraping elementdisposed at the cage, the scraping element being configured to removematter from a body lumen by applying a shearing force; a vacuum devicein fluid communication with an interior of the radially-expandable cagevia a window formed radially inwardly of one or more of the distalopenings; and wherein the window extends distally of the proximalopenings.
 6. The device of claim 5, further comprising an extractor, theextractor having a helical portion extending within the window.
 7. Thedevice of claim 5, wherein the struts include a wire that defines aportion of one or more of the distal openings and a portion of one ormore of the proximal openings.
 8. The device of claim 5, wherein thedistal openings are formed in a portion of the cage that graduallynarrows toward the distal end portion of the device.
 9. The device ofclaim 5, wherein the window is formed within a distal tube that extendsfrom a handle of the device to the distal end portion of the device. 10.The device of claim 5, wherein the vacuum device is in fluidcommunication with a plurality of openings formed in a tube extendingfrom a handle of the device to the distal end portion of the device. 11.A thrombectomy device, comprising: a first tube connected to a handle ata proximal end portion of the device; a second tube extending to adistal end portion of the device; a cage at the distal end portion ofthe device, the cage being adjustable between a contracted orientationand an expanded orientation by an axial motion of the first tube or thesecond tube, the cage including: a scraping element disposed between aproximal end portion of the cage and a distal end of the cage; proximalopenings and distal openings, at least one side of each proximal openingbeing defined by plural wires; wherein the plural wires are twistedtogether forming twisted wires; wherein the twisted wires include firstportions that define the proximal openings and second portions thatdefine one or more distal openings, the second portions being lesstightly twisted as compared to the first portions, and the scrapingelement is formed at an intersection of the first and second portions; apassageway extending from the cage to the proximal end portion of thedevice, the passageway being sized to receive material removed from abody lumen by the scraping element; and a vacuum in fluid communicationwith the passageway and with an opening formed in the second tube, thevacuum being configured to draw the material removed from the body lumentowards the passageway via the opening.
 12. The device of claim 11,wherein the passageway is formed within the second tube.
 13. The deviceof claim 12, further including a rotatable helical structure within thepassageway.